Baby name

Brenda

Can someone explain to me how it works if you’re a sr. Jr. And the III .?

My husband and I want to name our baby boy after him but just his first name, and the middle name would be different.

His dad doesn’t have a middle name but my husband is named after him except they added a middle name on his name and they said he’s still considered a jr.

We’re just really confused and need some help please and thank you 😊